Page 30 - Carbonate Platforms Facies, Sequences, and Evolution

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tion
type
here
(Fig.
(Fig.
1975;
nized:
of
Tidal
spicules
changes
(Fig. 1).
Shoal.
liassica ).
Esteban,
(2)
(Ferriera
platform.
7g).
7e),
Internal
interfinger
Platform
recognized:
the
brachiopods
type
and
fiat.
(Fig.
in
replaced
Three
Fazzuoli,
Open lagoon.
1976).
peloidal-skeletal
(1)
and
5).
(Paleodasycladus,
the
facies
by
lagoon.
marly intercalations.
interior.
Molluscs,
The
Formation).
beach-rock
The
corresponds
rare
1980).
Fenestral
(1) and (2) shoal facies).
slope
different
Skeletal
In
to
consists
open-marine
This
and
Platform-rimmed margin.
indicates
stratifi.ed,
peloidal-intraclast or unsorted
of
wackestone,
Solenopora
tropods and ostracods are rare.
From
zone
fingers with open-lagoon facies.
facies
an
Prevailing
following
echinoderms
vadose
stromatolitic
northern
off
consists
with
and
foraminifera.
west
stromatolitic
wackestone
have
ostracods and arenaceous foraminifera.
and
of
foraminifera
the
to
isolated
crinoid-coral
T.
faecal
well-sorted
with
pisolite
Type
been
open-marine
rare
Apuane
mudstone
east
(3)
boundstone
alternating, restricted-lagoon and tidal-fiat facies.
recog­
Thaumatopo­
(Thaumatoporella). Arenaceous foraminifera, gas­
organisms such as ammonites, radiolarians and for­
sections of the platform interior. The areal distribu­
containing intraclasts with pelagic organisms inter­
solenoporacean and dasycladacean algae, molluscs,
(Fig. 7a). Associated fossils in both facies are corals,
built by encrusting microbial organisms and algae
(Fig. 7c) or oolitic-oncolitic grainstop.e with lumps;
mounds
pelagic
oolitic
(Spirillina
algae
rella) are found in the intraclasts, as well as sponge
-intraclast grainstone
pellets,
and
is
trend at the top of the sequence occurs only in some
and are laterally discontinuous (Fig. 5). A regressive
(sensu
bounded by epicontinental basins (Boccaletti et al.,
aminifera, and locally reworked calcrete clasts and
boundstone
Alps,
is
Massiccio
where the Massiccio Limestone thins out, these strata
facies have been
These facies have a non-cyclic vertical distribution
platform
This is built by oolitic
Epicontinental basin. The Massiccio Limestone is
facies
shoals and locally by crinoidal-coral-mounds (type
irregularly
the
following facies equivalent zones can be recognized
Platform ramp-like margin. Type (3) shoal facies
to
Cocozza and A.
and
unit
local
listeri
types:
oides,
plates,
faunas
eastern
skeletal
breccias
(Diaspri,
recurring
platform
(Fazzuoli
prevailing
(1)
Gandin
basinal,
Sinemurian.
with
paleokarstic
at
stratigraphic
&
Ammonite
environment.
and
in
and
pink,
margin.
(Arietites
ammonite
foraminifera
Amaltheus
less
the
ammonites,
Upper
Pirini
wackestone,
levels:
features
comprises three,
Massiccio Limestone.
different
turbiditic
base of the sequence;
trations of ammonites (
locally
which
Breccia
Eoderoceras
are
(Calcare rosa a Crinoidi),
and
upper
and/or
The
Post-depositional processes
the
Dogger-Malm).
1980; Fazzuoli et al., 1981).
megabreccias
assemblages
bucklandi
common,
of
siliceous
part
Sinemurian
Ammonitico Rosso (Middle Lias)
margaritatus
irregularly
bodies
indicate
radiolarians,
but
Radrizzani,
older
These
is
laminated
stratigraphic
of
common.
crinoidal
in
contact is
packstone
an
and
are
Domain are associated with ophiolites.
shales
biozone)
document
the
Calcare
larger
with
the
olenopthychum
1981).
sponge
levels;
with
is
sharp
and
alternating
limestone
They are
along
enclosed
and
litho­
(2) red nodular marly lime­
stone (Fig. 8c) with shaly partitions and local concen­
the younger assemblages with Coeloceras psilocer­
The Massiccio Limestone underwent extensive fresh­
Protogram­
The Ammonitico Rosso lies unconformably on the
commonly found at the
Calcare rosso ammonitico),
is
and (3)
grey cherty limestone (Cherty Limestone-Calcare
grades .into marls with pelagic bivalves ( Posidonomia
moceras algovianum record Pliensbachian (Federici,
selcifero) with thin argillaceous interbeds commonly
Arietites
crinoid
lumachelles
(Fazzuoli, 1974b). The facies (Fig. 8d) are mudstone,
spicules
open-marine
different
with
Locally
sequence
locally marked by karstic breccias (Figs 2 & 9). This
Massiccio
blocks are found, enclosed in the Cherty Limestone
Lower
well
developed along the western margin of the Massiccio
karstic cavities or in the Cherty Limestone (Fazzuoli,
in
the
alpina M a rls, Toarcian-Aalenian) that in turn pass
cherts
1967). Higher in the sequence the Cherty Limestone
documented by
whereas
and locally show traces of dissolution. In the upper
part of the unit neptunian dykes (6-8 m wide) and
. calcite whereas marine cements are poorly developed
Ligurian
water cementation. Cements mostly consist of blocky